Former U.S. Sen. Norm Coleman of Minnesota has joined Mitt Romney's campaign as a special advisor, Romney's camp announced Wednesday. "His advice will be critical as I lay out my vision for improving our economy at home and strengthening our partnerships around the world," Romney said in a written statement. Coleman, who has working with the American Action Network, a conservative "action tank," follows former Gov. Tim Pawlenty, who signed on to the Romney campaign after ending his own bid for the presidency. Another prominent Minnesota Republican to back Romney is former congressman Vin Weber, originally a Pawlenty backer. By contrast, high-level Minnesota GOP endorsements for Michele Bachmann's presidential bid have been scarce. "The United States is facing an important moment in our nation's history," Coleman said in a statement released by the Romney campaign. "Whether it is turning around our struggling economy or maintaining our relationships with international allies, the next president must have the experience and leadership to keep America strong at home and abroad." Coleman, who lost a narrow reelection contest against Democrat Al Franken in 2008, praised Romney's past leadership in business and politics. "Electing someone who has not been tested by the fire of experience results in failure," he said. "The last three years have proven that." Coleman, a board member of the Republican Jewish Coalition, also called Romney "the best candidate to restore America's relationship with Israel."